1. Field of the Invention
The present invention relates to an optical information recorder, particularly to a device for recording information on a resist matrix by using a laser beam.
2. Background of the Invention
There is an optical system for recording video or audio information or the like on a disk-like recording medium. In the system, a photoresist is applied to a glass disk as a base plate to manufacture a resist matrix A focused laser beam irradiates the film of the photoresist on the resist matrix, with bit-by bit intensity modulation, depending on the information or the like to expose the film. The film is thereafter developed to have pits having various lengths and repetition periods to correspond to the information or the like. The information is thus recorded on the medium.
A conventional recorder called a cutting machine is used to record the information on the resist matrix in the optical system. In the recorder, a focusing unit converges the information recording beam onto the surface of the resist matrix. The focusing unit is supported by a carriage which is moved in the radial direction of the matrix by a drive mechanism a motor, a speed reducer and a moving screw which is rotated by the motor whose rotational frequency is controlled to regulate the speed of the movement of the carriage. Since the speed of the movement of the focusing unit is regulated only through the control of the rotational frequency of the carriage drive motor while the characteristics of the moving screw and the speed reducer which is coupled to the motor are not taken into consideration, there is a problem that the pitch between track portions (pit row portions) is made irregular due to the drive mechanism characteristics.